The long-term objective of this project is to address the public health importance of sleep disordered breathing and ultimately reduce morbidity through information gained from longitudinal, population-based, epidemiologic studies. We have shown that undiagnosed sleep disordered breathing is prevalent for both men and women throughout the range of middle age; multidisciplinary research findings suggest that untreated sleep disordered breathing may lead to significant behavioral and cardiovascular morbidity. At a time when public policy regarding resources for sleep disorders medicine and research will soon be forged, it is imperative that definitive data on the pathophysiologic significance of asymptomatic or mild sleep disordered breathing be forthcoming. We propose to quantify the etiologic role of hypothesized risk factors for sleep disordered breathing, describe progression of the pathophysiologic process, and test causal hypotheses of adverse health outcomes. The study will be conducted on a unique, established cohort of over 800 subjects, representative of middle-aged employed adults. Extensive baseline polysomnographic and other data are now available on this cohort; an additional cohorts of 50 perimenopausal women will be added for maximum study power. The proposed research will result in longitudinal data, over a five to nine year period, on multiple parameters of sleep, breathing, risk factors and outcomes. The independent relative risks will be calculated with multivariate techniques to express the temporal relationships for sleep disordered breathing etiologic factors and for consequences of sleep disordered breathing. The relative risks will be of direct application to public health estimates of: How much behavioral and cardiovascular morbidity would be eliminated if prevalence of untreated sleep disordered breathing were significantly reduced? How much reduction in sleep disordered breathing prevalence could be achieved by eliminating the modifiable etiologic factors? Should high risk groups be targeted for early detection or risk factor reduction programs?